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The results in Table 1.0 indicate that all four methods produced a resulting global minimum <br />factor of safety of 1.686 for the as -built slope, Since all of the factors of safety are <br />significantly greater than 1.50, which is used a basis for long -term stability, in our opinion, <br />the slope of the Gob Pile #4 is stable as constructed, Figure 1 below presents the results of <br />the analysis showing the slope as constructed and with the Janbu Method results. <br />Figure 1. Analysis results for Janbu simplified method which resulted in the lowest and <br />therefore most conservative Factor of Safety for the Gob Pile #4 slope as- constructed. <br />"-f"Y Factor <br />o.o00 <br />i0.500 <br />L.000 <br />1.500 <br />2.000 <br />2.540 <br />3.000 <br />3.500 <br />4.000 <br />4.500 <br />5.000 <br />3.500 <br />6.000+ <br />D) - 12&GEO Bmvie MinelPile #4 -2012 <br />Material- Native <br />Strength Type Mahr-CoOrrnh <br />Unit Weight. 125 IbA3 <br />cohesion: 100 psf <br />Faction Angie. 34 degrees <br />Water Surface. None <br />al: Gob <br />Ith Typo Moh,Coulomb <br />!eight: 110.5 lb,)13 <br />ion' 0 psi <br />n Angle: 34 degrees <br />CuNace -None <br />Method lanbu simplified <br />FS: 1.686330 <br />CONCLUSIONS <br />Since the analyses presented in this letter represent the CWDA #4 pile in its current <br />condition including moisture and grade, we recommend that the as -built condition be <br />accepted as is and that re- vegetation proceed as outlined in the mine's re- vegetataion plan, <br />That re- vegetation should result in continued increase in slope stability as long as surface <br />drainage is controlled and re- vegetation of the slope begins to take effect. <br />Thank you for the opportunity to work with you on this long -term project at the Bowie Mine <br />#2. If you have any questions about this analysis, please contact me at (970) 497 -8852 or <br />dan (dbuckhorngeo.com. <br />Respectfully submitted, y0 <br />o� +$+ •fie �` +� �`' <br />Daniel C. Quigley, 4PE, PG <br />Buckhorn Geotech, Inc. +,:[CA�� <br />�. k. <br />Bowie Thine #2 — CWDA Pile # 4 HA PN 05- 126 -GEO <br />REVISED As -Built Stability Analysis <br />